Chapter 2: Interview Questions & Answers Part 2
Q.51 What is the primary function of a router in a network?
Answer: A router is a network device that forwards data packets between different networks. It operates at the network layer (Layer 3) of the OSI model and uses routing tables to determine the best path for data transmission.
Q.52 Explain the difference between a router and a switch.
Answer: A router connects different networks and makes decisions based on logical addressing (IP addresses). A switch operates within a single network and uses MAC addresses to forward frames within that network.
Q.53What is the purpose of a default gateway on a router?
Answer: The default gateway on a router is the IP address used when a device needs to communicate with a device on another network. It serves as the entry and exit point for traffic leaving or entering a network.
Q.54How does NAT (Network Address Translation) work on a router?
Answer: NAT allows multiple devices in a private network to share a single public IP address when accessing the internet. It translates private IP addresses to a single public IP, enhancing security and conserving public IP addresses.
Q.55What is the significance of the router's configuration mode?
Answer: Configuration mode on a router allows network administrators to make changes to the router's settings. It is where commands are entered to define interfaces, set IP addresses, configure routing protocols, and more.
Q.56Explain the purpose of static routing and dynamic routing on a router.
Answer: Static routing involves manually configuring routes on a router, specifying the path that data should take. Dynamic routing uses routing protocols like RIP, OSPF, or EIGRP to automatically update and share routing information between routers.
Q.57How do you secure access to a router's command-line interface (CLI)?
Answer: Access to a router's CLI can be secured using methods like setting passwords, enabling SSH (Secure Shell), and configuring access control lists (ACLs) to restrict who can access the router remotely.
Q.58Describe the process of configuring an IP address on a router interface.
Answer: To configure an IP address on a router interface, you enter the router's configuration mode, navigate to the interface, and use the "ip address" command followed by the desired IP address and subnet mask.
Q.59What is the purpose of router interfaces?
Answer: Router interfaces connect the router to different networks. Each interface typically corresponds to a specific network segment and is configured with an IP address to facilitate communication within that network.
Q.60How does a router determine the best path for data transmission?
Answer: A router uses routing tables to determine the best path for data transmission. These tables contain information about known networks and the associated next-hop routers, allowing the router to make informed forwarding decisions.
Q.61 What is the purpose of a VLAN (Virtual Local Area Network)?
Answer: VLANs are used to logically segment a network into smaller broadcast domains, improving network efficiency, security, and manageability. They group devices regardless of their physical location into broadcast domains.
Q.62 Explain the difference between a hub, a switch, and a router in a network.
Answer: A hub operates at the physical layer and broadcasts data to all connected devices. A switch operates at the data link layer, filtering and forwarding frames based on MAC addresses. A router operates at the network layer, making forwarding decisions based on IP addresses.
Q.63 What is STP (Spanning Tree Protocol) and why is it important in switched networks?
Answer: STP is a protocol that prevents loops in Ethernet networks by identifying redundant paths and blocking them. It ensures a loop-free topology, preventing broadcast storms and network instability.
Q.64 How does the MAC address table work in a switch?
Answer: The MAC address table in a switch maps MAC addresses to the corresponding switch ports. When a frame arrives, the switch uses this table to forward the frame only to the port where the destination MAC address is located, reducing unnecessary traffic.
Q.65 What is the purpose of the VTP (VLAN Trunking Protocol) in Cisco networking?
Answer: VTP is used to synchronize VLAN information across multiple switches in a network. It helps in maintaining consistent VLAN configurations, reducing the administrative overhead of manually configuring VLANs on each switch.
Q.66 Explain the concept of broadcast domains and collision domains in switched networks.
Answer: A broadcast domain is a logical division of a network where broadcast traffic is contained. A collision domain is the segment of a network where collisions can occur. Switches reduce collision domains, enhancing network efficiency.
Q.67 What is the difference between half-duplex and full-duplex communication in networking?
Answer: In half-duplex communication, devices can either send or receive data at a given time, but not simultaneously. In full-duplex communication, devices can send and receive data simultaneously, doubling the potential bandwidth.
Q.68 How does Port Security enhance network security in a switched environment?
Answer: Port Security restricts access to a switch port based on the MAC address of the connected device. It helps prevent unauthorized devices from connecting to the network and protects against MAC address spoofing.
Q.69 What is the purpose of the EtherChannel in Cisco networking?
Answer: EtherChannel is used to bundle multiple physical links into a single logical link, providing increased bandwidth and redundancy. It enhances fault tolerance and load balancing across the aggregated links.
Q.70 How does QoS (Quality of Service) play a role in switch configuration, and why is it important?
Answer: QoS prioritizes and manages network traffic to ensure that critical data gets higher priority. In a switch, QoS can be configured to prioritize certain types of traffic, such as voice or video, ensuring optimal performance for those applications.
Q.71 How do you create a VLAN on a Cisco switch?
Answer: To create a VLAN on a Cisco switch, use the vlanvlan-id command in global configuration mode. For example, vlan 10 creates VLAN 10. After creating the VLAN, assign it to a switch interface using the switchport access vlanvlan-id command in interface configuration mode.
Q.72 What is the purpose of the "show vlan" command, and how can it be used in troubleshooting?
Answer: The "show vlan" command displays information about configured VLANs on a switch. It provides details such as VLAN names, VLAN IDs, and associated switch ports. In troubleshooting, this command helps verify VLAN configurations and quickly identify any misconfigurations.
Q.73 Explain the difference between access ports and trunk ports in VLAN configuration.
Answer: Access ports are used to connect end devices to a specific VLAN, while trunk ports carry traffic for multiple VLANs. Trunk ports use encapsulation protocols like 802.1Q to tag VLAN information on frames, allowing switches to differentiate between VLANs.
Q.74 What is the purpose of the "native VLAN" on a trunk port, and how is it configured?
Answer: The native VLAN on a trunk port is the VLAN that carries untagged traffic. It is essential for interoperability between switches. To configure the native VLAN, use the switchport trunk native vlanvlan-id command in interface configuration mode.
Q.75 How do you troubleshoot connectivity issues in a VLAN?
Answer: Troubleshooting VLAN connectivity involves checking VLAN configurations, verifying trunk links, ensuring correct VLAN assignments on switch ports, and using tools like the "show vlan" and "show interfaces" commands. Also, check for consistent VLAN configurations across interconnected switches.
Q.76 What is VLAN pruning, and why is it useful in a switched network?
Answer: VLAN pruning is a feature that prevents unnecessary traffic from being sent over trunk links. It dynamically removes VLANs from trunk links if they are not present on the destination switch, reducing unnecessary broadcast and multicast traffic.
Q.77 How can you prevent VLAN hopping attacks in a network?
Answer: VLAN hopping attacks involve an attacker gaining unauthorized access to a VLAN. To prevent such attacks, implement techniques like VLAN access control lists (VACLs), dynamic trunking protocol (DTP) security measures, and ensuring that unused ports are either disabled or placed in an unused VLAN.
Q.78 What is the purpose of the "VTP pruning" feature, and how does it work?
Answer: VTP pruning is used to optimize bandwidth usage by preventing unnecessary broadcast traffic from being forwarded over trunk links. It dynamically prunes VLANs that are not needed on a specific trunk, based on the VLAN information exchanged via VTP.
Q.79 Explain the concept of Voice VLAN and how it is configured.
Answer: Voice VLAN is used to separate...
